Device with flow medium stratification for positioning and/or transporting unit loads

ABSTRACT

The device disclosed comprises a support surface for unit loads, on which a load-bearing flow medium cushion, in particular an air cushion, can be constructed. Passages in the support surface communicate through a channel with a pressure source for the flow medium. At least part of the support surface consist of a body permeable to the flow medium and made of a sintered material, and which is inserted in the passages which can be connected through the channel to the pressure source.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national phase of PCT/CH89/00109 filed 7 June 1989and based upon Swiss national application 2203/88 filed 9 June 1988under the International Convention.

The present invention relates to a device with flow mediumstratification for the positioning and/or transport of unit loads,particularly flat unit loads, wherein a flow-medium cushion,particularly an air cushion; can be built up over a support surface forthe piece goods, passages in the support surface communicating throughchannels with a pressure source for the flow medium.

BACKGROUND OF THE INVENTION

Devices of the above-mentioned type are advantageously used for a gentleand noncontact positioning or moving of sensitive goods, such as paperwebs or glass plates, records and CDs, but also silicon plates forsemiconductors and the like.

Therefore, the passages provided in the support surface and as a rule,in flow connection with a compressed air source, are nozzles whichcompress the air underneath the piece good, the latter being then keptin suspension by the air.

Thereby, particularly where large surfaces are concerned, a large numberof nozzles is required, leading to a high cost of the installation and ahigh consumption of flow medium.

Besides, if such systems are used in a so-called clean room, whereinfrom the ceiling a weak, downwardly directed air stream is constantlymaintained in order to keep down the dust and the like,counterproductive air turbulence can occur, due to the punctiform exitof the air from the nozzle.

OBJECT OF THE INVENTION

It is therefore the object of the present invention to create a deviceof the aforementioned kind, which allows for a "gentle" air-cushionbuildup.

SUMMARY OF THE INVENTION

According to the invention, this object is attained in that at least oneportion of the support surface consists of bodies made of a flow-mediumpermeable sintered material, these bodies being inserted in the passagesconnectable to the pressure source via channel means.

These measures taken according to the invention allow the exit of arelatively large air flow on the upper side of the support surface,without the point blasting effect, whereby a vertical surface flow iscreated without materially influencing the existing flow conditions,leading to a quasi-static air cushion, appropriate for any size of thearticle supported.

The selection of the sintered material, which may be carbon, ceramic orthe like, of the size of the flow-permeable bodies, of their density persurface unit, as well as the selectable flow pressure allow an optimaladjustment of the quasi-static air cushion to any use.

For an article of a smaller area, such as CDs or trays (platforms)supporting small articles or the like, the support surface with theflow-medium permeable bodies of sintered material form channel-likeguide tracks with lateral borders.

It is important to create an effective advance of the piece good.

If this advance is created in the usual manner through advance nozzleslocated in the lateral borders, the installation is not suitable forclean rooms, for the aforementioned reasons.

If belt conveyors with centrally arranged entrainment means are used,considerable difficulties result in connection with an accumulation ofthe usually highly sensitive articles.

Therefore, a suitable development of the mentioned device can beconsidered the arrangement wherein the support surface is a part of theguideway of an accumulation conveyor and is pentrated by at least onedragging conveyor slit, through which entrainment means extend, each ofthem embracing on the belt side at least three roller or cylinder bodiesarranged in the direction of travel, succeeding one another at equaldistances and height-staggered with respect to each other, the roller orcylinder bodies being each partially wrapped by the belt and formingwith the belt a slip drive for the entrainment means.

As a result, the articles carried by the air cushion have a secureentrainment connection with the endlessly running belt up to theaccumulation point, where they stop due to the slip between belt andentrainment means.

Due to the relatively uncomplicated measures taken for this slip drive,it is practically possible to vary at will the slippage, respectivelythe holding force and to adjust them to the existing conditions, throughthe selection of the lateral distance between the rollers or cylindersand/or of their surface structure.

In order to avoid the transmission of the impact pressure by the piecegoods, it is advantageous to provide stop means on the entrainmentmeans, which cooperate with the neighboring entrainment means inmaintaining the distance.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the invention are described with the aid of theaccompanying drawing, in which:

FIG. 1 is a longitudinal section through the support surface of a devicewith flow medium stratification for piece goods; and

FIG. 2 is a schematic perspective view of the device according to theinvention in the form of an accumulation-type conveyor, partly brokenaway.

The device with flow medium stratification for the positioning and/ortransport of piece goods, particularly flat articles, comprises asupport surface 1 for the piece goods and has passages 5 which are inflow connection with a pressure source of the flow medium, usually air,via channel means 4.

It is essential for the invention that at least one portion of thesupport surface 1 be formed by flow-medium permeable bodies 2 made ofsintered material, which bodies 2 are inserted in the passages 5connectable over channel means 4 with the pressure source 3.

Thereby, an air discharge over a relatively large area on the top sideof the support surface is possible, resulting in a superficial, verticalair current which forms a quasi-static air cushion.

The choice of the sintered material, such as carbon, ceramic and thelike, of the side of the flow-medium permeable bodies 2, the density ofthe arrangement surface unit and the selectable flow pressure allowthereby an optimal adjustment of the static air cushion to any use.

For instance, a type of such use can be seen from FIG. 2.

This figure shows an accumulation-type conveyor, wherein the supportsurface 1 is a part of the guideway 1' with lateral guides 12 and servesfor the transport of CDs, for example.

Through the middle of the guideway 1, a dragging conveyor slit 6extends, for the longitudinal guiding of a plurality of continuouslyrunning entrainment means 7 (only one such entrainment means is shown).

Each entrainment means can thereby be guided with a flat guide piece 7'in the dragging conveyor slit 6, or can be supported on guides viarollers (not shown), so that the entrainment means can run unimpairedwith the system along the conveyor path.

Each entrainment means 7 continues on the belt side preferably with achassis 14, which here carries three roller respectively cylinder bodies8 and 9, succeeding one another at equal distances in the traveldirection of arrow 15 and are height staggered with respect to eachother. These roller respectively cylinder bodies 8 and 9, which can befreely revolving or nonrotational, are each partially wrapped by a belt10 and form together a slip drive for the entrainment means 7, wherebythe belt is as a rule driven as an endless belt, which is known per seand requires no further explanation.

As mentioned, the entrainment means 7 move highly sensitive CDs 13,which here float on an air cushion over the support surface 1 of theguideway 1'.Therefore, according to the embodiment example of FIG. 1,one portion of the support surface 1 consists again of flow-mediumpermeable bodies 2 made of a sintered material, these bodies 2 beinginserted in passages 5 which via openings 16 are in flow connection withthe pressure channel 4 for the floor medium, e.g. air.

Thereby, it is also possible to provide such air-exit openings in thelateral guides 12 (not shown), in order to create lateral air cushionsto prevent the piece goods from hitting the lateral guides 12.

In order to prevent an immediate overrun of the piece goods 13 in caseof jamming, each entrainment means 7 is provided with a stop means 11for maintaining the distance, which cooperates with the forerunningentrainment means 7.

If, as a result of accumulation at the stop means 11, an increasingimpact pressure is generated, as indicated by arrow 17, the belt 10continues to travel in the direction of the arrow 15, as a result of theslip between belt 10 and rollers 8 and 9, while the respectiveentrainment means 7 and the CD 13 moved therewith via for instance pin18 stops.

From the preceding description a device results which is not onlycapable to produce practically a quasi-static air cushion with minimalair consumption, but which can also be used as an accumulation-typeconveyor in so-called clean rooms.

I claim:
 1. An apparatus with flow medium stratification for thetransport of articles comprising:a support surface for the articlesforming a load-bearing flow medium cushion, at least one portion of thesupport surface consisting of flow-medium permeable bodies made of asintered material, said bodies being inserted in passages for a flowmedium; a pressure source for the flow medium; channel means connectingsaid passages with the pressure source; a guideway of anaccumulation-type conveyor and penetrated by at least one draggingconveyor slit said support surface forming part of said guideway;entrainment means for displacing said articles and extending throughsaid slit and having on a belt side at least three roller bodiessucceeding one another at equal distances in a travel direction andheight-staggered with respect to each other, each roller body beingpartially wrapped by an endlessly running belt arranged underneath theguideway and forming with the belt a slip drive for the entrainmentmeans.
 2. An apparatus according to claim 2, wherein the entrainmentmeans are provided with stop elements.